Conventional methods for manufacturing cellulose acetate membranes and hollow fibers suitable for medical use include a step in which the membranes are impregnated with an aqueous solution comprising a substantial concentration of glycerin (also termed "glycerol") to maintain hydration of the cellulose acetate until time for their intended use. Because glycerin is conventionally believed to be critical to the maintenance of CA-membrane permeability, medical devices (such as hemodialyzers, hemofilters, hemodiafilters, and the like) are conventionally packaged, shipped, and stored while impregnated with substantial amounts of glycerin. Elimination of the glycerin or replacement of the glycerin with any other substance is conventionally believed to cause an unacceptable degradation of permeability and, hence, membrane performance.
Unfortunately, according to conventional practice, the glycerin impregnant is at a concentration in the membrane that conventionally requires thorough rinsing to remove substantially all the glycerin before use. Having to perform such a pre-use rinse is cumbersome and inconvenient and consumes valuable time and resources in busy clinics.
Thus, there is a need for methods for manufacturing cellulose acetate membranes, and for manufacturing medical devices incorporating such membranes, that eliminate the need to maintain a substantial concentration of glycerin in the membranes from time of manufacture until time for their intended use.
There is also a need for methods for manufacturing cellulose acetate membranes, and for manufacturing medical devices incorporating such membranes, that contain an impregnant consisting substantially of water serving to maintain membrane permeability from time of manufacture until time of medical use of the membranes and devices.
There is also a need for cellulose acetate membranes, as well as medical devices comprising such membranes, that can be infused with a priming solution in preparation for medical use without having to discard the priming solution.